Lower Fox River/Green Bay, WI

A.39 Lower Fox River/Green Bay, WI

A.39.1 Summary

Environment:	Freshwater river and embayment
Scale:	Full
Contaminants of Concern:	PCBs (primary), dioxins and furans, pesticides, arsenic, lead, and mercury
Source Control Achieved Prior to Remedy Selection?	No
Final Remedy:	MNR (20 river miles - Fox River, 2650 acres - Green Bay); cappingTechnology which covers contaminated sediment with material to isolate the contaminants from the surrounding environment. and dredging (19 river miles – Fox River; 50 acres - Green Bay)
Expected Recovery Time:	40 - >100 years (not considering that sediment remediationThe act or process of abating, cleaning up, containing, or removing a substance (usually hazardous or infectious) from an environment. in upstream source areas could reduce recovery time).
MNR viewed as a success?	Not yet determined

A.39.2 Site Description

This area includes the last 39 miles of the Lower Fox River and Green Bay. Green Bay is an extension of Lake Michigan in eastern Wisconsin. The Fox River Valley is heavily urbanized and industrialized with a high concentration of paper mills. The primary sources of contamination at this site are past discharges from production and recycling of carbonless copy paper in the Fox River Valley, ongoing releases from upstream sediments.

The site has been divided into five OUs. This case study focuses on OU 2 (Lower Fox River from Appleton to Little Rapids) and OU 5 (Green Bay), which rely primarily on natural processes for remediation.

The paper industry has been active on this site since the mid-1800s. Water quality problems have been noticed since the early 1900s. PCBs found in the water and marine sediments are attributed to recycling carbonless copy paper in the Fox River Valley. Since the industrial PCB production has stopped, it has been established that 95% of the PCBs found in the water originate in the sediments. PCBs were stopped in the production of copy paper in 1971. PCB concentrations in fish have significantly decreased, particularly in the 1970s. However, since the 1980s the rate of decrease has slowed and it is unclear if PCB concentrations in fish will plateau or continue to decease.

CSM Summary: The primary natural recovery processes for this site include dispersion1) Pollutant or concentration mixing due to turbulent physical processes; 2) A distribution of finely divided particles in a medium. and physical isolation. Numerous empirical measurements were input into fate and transport models. Data from these models were then input into bioaccumulationThe accumulation of substances, such as pesticides, or other organic chemicals in an organism. Bioaccumulation occurs when an organism absorbs a toxic substance at a rate greater than that at which the substance is lost. Thus, the longer the biological half-life of the substance the greater the risk of chronic poisoning, even if environmental levels of the toxin are not very high. models to predict sediment concentrations as well as ecological and human health risks for different remedial scenarios.

A.39.3 Remedial Objectives

Remediation risks for this case study include ecological and human health risks from PCBs, dioxins and furans, arsenic, lead, and mercury.

Ecological: Significant risks to ecological receptors are present. Reproductive impairment and physical deformities have been noted in terns, cormorants, and bald eagles. This is believed to be, at least in part, due to PCB exposures.
Human health: Unacceptable cancer and non-cancer risks were found for recreational anglers and high-intake fish consumers.

RAOs for sediments as stated in the 2002 and 2003 RODs include:

Protect humans who consume fish from exposure to COCs that exceed protective levels.
Minimize the downstream movement of PCBs during implementation of the remedy.

A.39.4 Remedial Approach

Final selected remedy: MNR (20 river miles - Fox River, 2650 acres - Green Bay), capping and dredging (19 river miles - Fox River, 50 acres - Green Bay).

MNR was selected as the primary remediation approach for OU 2 and OU 5. Some minor dredging will be carried out in OU 5 at the river mouth (50 acres) and in a downstream depositional area of OU 2 (8 acres).

MNR was selected for OU 2 and OU 5 because active remediation would not have produced significantly better results. Capping and dredging were not implementable in OU 2 and OU 5 due to shallow bedrock and high dispersion potential (OU 2), as well as an excessive volume of low-level contaminants in Green Bay (OU 5).

The use of MNR as the optimal remediation approach was validated through several models. Numerous empirical measurements were input into two fate and transport models including historical bathymetric surveys, sediment coring and vertical PCB profiling, sediment bed stability studies, time-trend analysis comparing direct discharges of PCBs from paper mills with steady-state releases from sediments. The fate and transport models predicted PCB concentrations in water and sediments that were then input into two bioaccumulation models calculating the contaminant transfer within the marine food web. Using these two types of models sediment concentrations as well as ecological and human health risks could be estimated for different remedial scenarios.

A.39.5 Monitoring

The RODs specify that OU 2 and OU 5 will be subject to a 40-year monitoring program. Risk reduction monitoring activities will include:

surface water quality testing to determine downstream transport of PCB mass into Green Bay
fish and waterfowl tissue sampling for human receptorA plant, animal, or human that is typically the focus of a risk assessment following the direct or indirect exposure to a potentially toxic substance. risks
fish, bird, and zebra mussel tissue sampling for ecological receptor risks
possibly surface sediment chemistry analysis in MNR areas to assess potential recontamination from upstream sources
population studies of bald eagles and double-crested cormorants for reproductive viability

The remedial design plan was scheduled to be finalized in late 2008 or early 2009.

RAO’s/project objectives achieved? Baseline monitoring of PCB concentrations in MNR-designated areas was completed in 2007. The MNR remedial design plan will be finalized in 2009.

Expected recovery time: 40 to over 100 years. This time frame does not take into consideration sediment remediation in upstream source areas, which could reduce the recovery time.

Projected monitoring costs: $7,000,000 to $13,000,000

A.39.6 References

Fox River Cleanup Group, www.foxrivercleanup.com.

Publication Date: August 2014

Permission is granted to refer to or quote from this publication with the customary acknowledgment of the source (see suggested citation and disclaimer).